Air brake systems for automotive vehicles



May 3l, 1960 R. H. GEORGE AIR BRAKE SYSTEMS FOR AUTOMOTIVE vEHcLEs FiledDec. 2o, 1955 2 Sheets-Sheet 1 kmq INVENTOR /Foerf Hed/ye ATTORNEY May31E, 1960 R. H. GEoRGE 2,938,753

AIR BRAKE SYSTEMS FOR AUTOMOTIVE VEHICLES Filed Dec. 20, 1955 2Sheets-Sheet 2 ATTORNEY.

United u States Patent" l;

AIR BRAKE SYSTEMS Fon-AUTOMOTIVE vnrncLns Fued'nec. 2o, 1955ser. No.554,253:

6 Claims. (Cl. sos-wsa)k This invention relates to air brake systems forautomotive vehicles, and it relates more particularly to air brakesystems adaptable for use` onbeavy vehicles such as trucks, buses,tractors, and' tractor trailers.

In the use of heavy automotive vehicles manyvr collisions andiwreckslarecaused by air brake failures, as well as kby failures of the drivers touse the brake systems properly.

Itis,` of course, well known that when a compressor in a heavy vehicleairy brake system is idling, as ,when drifting on a down grade, thesupply of compressed air needed for .proper braking is not ordinarilymaintained sufficiently,` and it is equally well known that when a truckor tractor, provided with an ordinary air brake system, has beenstanding for. sometime, it frequently happens that, due to leakage inthe system, air under suicientpressure is not immediately availableyfor'braking purposes, and accidents frequently occur `,through failureof the operators to recognize these, conditions.

It is a common practice for the operators of heavy vehicles,particularly on down grades, to indulge in a practicev commonly calledfanning which consists in making a number of light brake applications insucces sion; The effect of this practice is to-reduce the available airpressure in the reservoir tanks to a point where there is no longersufficient air under tbe requisite pressure to operate the brakes, and'thereby to properly controlthe movement of the vehicle. e

The normal air pressure commonly used in automotive practice has beenfromv about 85 to 105v pounds per square inch, but as the vehicle loadsare constantly be-l coming greater, there ,isl a ltendency lforV the Yoperatorsrto adjust the governorvalves upward in an endeavor to maintainabout 100 to 120'pounds pressure per square inch in the reservoir tanks.

y Generally,the feeling of the operator is that, when the alarm, nowrequired in new vehicles by Interstate Commerce regulations, isactuated, there is still somelair available sothathe can continue ontosomepoint where the necessary correction canbe made more conveniently.It is not generally understood by the operators that,.for the purpose ofobtaining a pressure of 100 pounds per square inch, the air must becompressed from approximately seven times the resulting volume.

When a brake application is made by use of. theV .air from a reservoircarrying 1 00 pounds pressure, the use of the air Yin a single brakeapplication will ordinarilyl result ina reduction of only 4 or 5 poundsdue to the large volume compressed, However, when tbe air in thereservoir has been reduced to about 60'pound's, each brakeapplicationwill ordinarily reduce the available pressure by more thandouble the reduction when operating at the above mentioned'higherpressure.

Vltwill therefore be easily understood that wheneverl tbeair in thereservoir tank falls to below the minimum reduce thefpressure to .apoint where thefbrakes Willa-.1o

2,938,753 A Patented May 3i, 1960 longer be operative,.with theresultant loss of control and danger of collision.

With the yforegoing in View, the principal object of the presentinvention is to provide certain improvements in brake systemsv of heavyvautomotive vehicles whereby the brakes willV beV automatically appliedin the event of diminution of the, pressure inthereservoir tanks below apredetermined amount.

A further object of the present invention is to provide in brake system,of the character aforesaid, an arrangement whereby airunder pressurewill be automatically .passed from the compressor directly to the brakesfor the purpose of actuating the same whenever thereis little or no airVundersulicient pressure in the reservoir tank available for suchpurpose,` and this vwithout any. actionor controlby the operator. Y e

A further object of the present invention is to provide anair brakesystem, of tbe .character aforesaid, which will be applicable toautomotive vehicles of various types and, particularly, tothose in whicha detachable trailer is coupled to a tractor.

' further object of the present invention is to provide, inan air brakesystem of-the characteraforesaid, a novel arrangement of` parts, wherebysaid systems may, with butrlittle change, be caused to operate safelyunder the various conditions occurringv in practice.

Y The nature and' characteristic features of the present inventionwillbe morereadily understood from thefollowing description takeninconnection with the accompanying drawings formingpart hereof, infwhich:

. Figure 1 is a diagrammatic view of an air brake system `for heavyautomotive vehicles embodying the main features of the presentinvention, the particular arrangementtherein shown being applicable totractor and trailer type vehicles;

Fig. 2 is a longitudinal central sectional view of a special valve usedin the brake system of thepresent invention, Vthe same comprising oneofthe principal novel devices ofthe invention;

Fig. 3 is a similar view of a special control valve comprisingfanotherof the novel devices of the present inventiomsand Fig, 4 is a viewsimilartoPig. 2, vof a special valve comprising another of the noveldevices of the present invention.

It should, of course, be understood that the description and drawingsherein are illustrative merely, and .that various modifications andchanges may be vmade in the structure disclosed without departing fromthe spirit of the invention.

Referring to the drawings, in tbe particularY embodiment of theinvention therein shown, the general arrangement ice of the brakingsystem of the present -inventionis in many pump 10, and usually a pairof reservoir tanks Y11 and' 12 for receiving the air which is compressedby said compressor or pump 1i). The tractor wheels (not shown)are'provided withrigbt and left handv air operated brakes 13 and 14 toand from which the air ordinarily passes under the control of theusualand ordinary footoperated brakelvalve 15, and also, a-hand operatedvalve 16, which passage of the independently of the tractor brakes inthe'usual manner.

In those instances in which a trailer, coupled to the tractor, is used,the trailer is ordinarily provided, with a reservoir tank 17 Vvfromwhich theair under .prressureirr'iayV be transmitted to and from therightand` jleft '.handair operated trailer brakes 18 and 19 through thepipes 21 and 22'respectively under certain conditions. l I j The traileris also provided withja',soacalledrfrelay valve connected inthe Yusualand customary manner to the trailer brakes 18 and 19, by pipejlinesZland 2:2, to the reservoir tank 17 by pipe line V23,V andjto theV `pipeline 24 for supplying the air to the'traler reservoir tank 17 from themain reservoir tanks Y11 and"12 carriedA by the tractor, and to the pipeline 28 for controlling the air Vto vand fromthe trailer brakes Y 18andlg' Y .Y Y l ,u v y...I-V1 In airbrake systems'for heavy vehicles,aswhere'to# fore provided, it was vcustomary to connect theair'compressor directlytothe main reservoir; tanks, but-in ac-4corda'nce with the present 'invention thereV is additionally provided aspeciallvalve 30 for by-passingthe aircoming from the compressor 10directly to the brakes, wheneverA the pressure in the reservoir tanksfalls below a predetermined amount.V This valve is shown in detail inFig. 2 of the drawings;AV i '3 VThe special valve 30 comprises'a mainhousing 31, having-an internal'cylindrical'bore 32, and near one end anextension 59, which projectsfromxthe end of valve` member 45 through thevalve seat bushing 41.

The head or guide member 58 is provided with pas4 sageways 60 to permitthe "tlow of the air from the inten'or of the valve housing 31, throughthe sleeve like extension 39 thereof to the outlet nipple 43 to whichthe pipe line 44 is connected,` whenrthe valve face 48 is pushed fromits seat by the coil springV 57.J v

The other end of'the'coil spring 57 bears against a ring member 61which, as shown,.is Yin turn seated on another ring member 62,of `asimilarY size and :shape` By substituting other ring members .ofdiz'erentthicknesses, the tension of the coil spring 57 maybe adjustedto the desired operating pressure;

The valve housing31 s also provided, intermediate its ends, withanoutwardly ,projecting portion 63 through which passageways 64,V 65 and66 are bored. Certain of .the holes, through which tools are insertedforA boring the aforesaid passageways, are closed by meansof threadedplugs 67 `and 68, whereas, one of said holes 69 isv` used for theconnection o'fA a pipe' 70 leading'to'a relief Y valve 7 1 to preventdamage to the 'valve 30vin` the event of the housing-31`there isprovided, onV one side,-a'n inlet nipple 33, for the purpose ofconnecting pipeline 34 extends from the air compressor or pump 10.

' On theV end of the valvehousingl, adjacent the side inlet nipple 33,there is mounted a bonnet 35 having 'an outletY nipple 36 f orY thepurpose of connecting a pipe lineV 37 VVextending to thefreservoir tank11 and through pipe line 38 to reservoir tank 12, for the normal main-ktenance of the air'under pressure in said tanks. I The bonnet alsoserves to maintaina flangedbushing 39 in position to provide a valveseat at that end of the housing 31. Y Y

Atf the other end of the `housing 31 thereis mounted avsleeve likeextension 40 ofthe housing serving to'hold and retain a anged bushing 41which provides -a valve seat at that end offthe housing 31.

Which Mounted on the end of the sleeve like extension 40 ofYY ofY theair reaching anV abnormal pressure in that'part of the'psystern to whichsaid relief valve is'connected.k It'will be' noted thatv the valvemember v45, in the absence of sutiicient pressure in the reservoir.'tanks 11 and: 12, Vwill berimpelled by the coil-spring 57, to Vcause thevalve face 47 Lof the valve member 45to be seated on thebushing3u9. "r fWhen 'thevalve member v45 is in ythis position, vair owing fromY thecompressor` or pump 10 will passaround the valve* member 45 and through:the Ipassageways 64',l 65 and 66 to the other end of the housing 31, andas the .f valveJ face 48 provided atthat endV will then be moved valve30is a bonnet 42 provided with an outlet nipple 43 froinzwhich extends apipe line 44-for a purpose to .be presently explained. l

from'its seatthe airwillowth1 -ough the hanged-bush# ing V41,` throughthe-passageways 60 inthe head member 58,ai1dethrough the sleeve 40 tothe outlet nipple43; and thence through pipe line 44 to special controlvalve 72. AWhenyhowever, the airbrake; Vsystemis functioning' properlythe air in the reservoir tanksv 11 and 12' is of suiiicient pressure toovercomethe tension of the coilY spring '57,the air from thecompressor'or pump will tlow -pastthe valve face 47 near the inlet endof the housing,` thence through the anged bushing 39, and throughthenipple-"36 tothe pipe 37 connected thereto, directly to` the reservoirtanks 11 and 12 for normal f use when re quired from time to time. 1 YThefpipe line44 extends tol one end of the special conseated, when.operatedy as Vhereinafter setV forth, on the valve seats providedpbythe hanged bushings 39am-l 41 at the respective ends of the'housing 31.t Y

Intermediate the ends of the valve` memberVr iis ari enlarged portion 49constituting, in effect, a pistonV in vest which is provided, inan,annular recess 50 therein, a

packingV ring 51 to' prevent passage of the air past said piston likeportion 49.V Y

'Ihe interior of the housing. 31 is also provided,- with an ,mwardly'projecting annulus 52,- in conjunction withY which the cylindricalportion 46 of the valve member 45 Yis provided with a groove 53, inwhich a packing ring 54 is located, to prevent the passage ofair. pastsaid annulus 52.v The annulus:52;is positionedwithinffthe bore 32 of thevalve housing 31, a suicient distance from the piston portion 49 ot'`valve memberv45to provide a central chamber 55 whichpis 4infreecommunication with the exterior through a port 56.v

o r guide member V58, which is mounted on the :end of.V

Y 1d The sleeve like extension 40, Vwhich is Vmounted onthe p pressureis .applied of: providing the usual-separate con` Y is/shown moreparticularly inrFig. 3 'ofthe drawingsand willlherehxafter bedescribed'in detail. `'Ille other end of'th'elspecial control-valve 72isconnected tothe reset-j voir tanks 11 and 12 as, for example, by meansof "a pipex l73brarichirlgffrom pipe line180, hereinafter refer-red to,Iwhich extends'ffrom the reservoir tanks' 11jand12.Y 1

"The main controlpipe line=74, Ywhich extendsfromthe reservoir tank 12to the compressor 110, and has connected thereto the compressor governor75also has, if desired,A` apressure gauge 76, a low pressureV alarm 77,vanairzstarting motor 78, and 'a v'vir'nishieldA wiper 79,' all ofv whichparts are operable through the pressure oftherair coming from-theVreservoirtank 12. v Y

. Thecontrol of the,V brakes is Yordinarily and usually effectedby"meansf ofi-the air under normal operating vpressurepassing from thereservoirA `12throughlpipe line 'to Vthe'foot operated brake valve151and thence, whenthe foot valve 15 is actuated, through pipeline 8-1to'a doublefacting. check valve ,82, to which' is connected aL pipeline83 which .extends to the tractorbrakes 13 and 14,respectively. Y Y

A stop light switch 84 maybe connected tothe` pipe line 83A to actuate.the stop light .whenever the" airunder fFor .the purpose to the tractor:brakes' -n the :usual' ganarse trol of the trailer brakes whereby `thesame maybeapplied, when Yso desired, independently of the tractorbrakes, there is provided'a Yhand valve 16 to which a branch pipe 85extends [from the pipe line 80. `The hand valve 16 is connected bypipeline 86 to a double acting check valve 87, which is. also connected by'pipe line 88 to the foot operated brake valve 15, for the operation ofthe trailer brakes simultaneously with the 'tractor brakes when the footoperated valve .is actuated.

A pipe line 89 extends from thesdonble acting check valve 87 to anotherdouble `acting check valve 90, which is connectedby pipeline 91 totrail'encoupling 92, which in turn is connected to the pipeline 28 whichextends to the relay valve ofthe trailer.

The double acting-checkfvalve 90-isr cross Aconnected Iby pipe line 93to thedouble acting check-valve 82, hereinbefore referred to,;and this,line 93 :in turn is. connected by pipe line 94 `toa nipple i101 of thepressure control valve 72 shown in- Fig. 3 of the drawings, vand whichwill be hereinafter more vfullyV described. The arrangement is such thatwhen: the aircoming, vdirect from the compressor is permitted tofowYthrough. the special valve 30, and pipe line 44, to control' valve 72,said air under pressure coming Vfrom the compressor will be applied tothe tractor brakes and tothe trailer relay valve 20 to cause the trailerbrakes to be operated.

The special control valve 72, which is shown more particularly in Fig. 3of the drawings comprises a housing made of two parts, 102 and103,having an internal bushing 104 provided with a ange 105, which isgripped between the abutting portions of the housing parts 102 and .103.

The interior of the housing part-102 -isY bored through, as at 106, toprovideV a cylinder in which a piston 107 is slidably mounted. ThepistonV 107 is provided with an annular groove 10S in which a packingring 109 is mounted lto prevent leakage past the piston.

The portion 102 of the housing of special valve 72 is provided, at theend thereof in which the piston 107 is located, with` a nipple 110 towhich the pipe line 73 is connected. A coil spring 111 is interposedbetween the piston 107 and thebushing 104, serving to impel the pistonV107 to the end of the cylinder Whenever the pressure in the reservoirs11 and 12, and hence in theV pipe line 80, to which pipe line 73 isconnected, is not suiii cient to overcome the tension ofthe spring 111.

The portion 103 in the housing of the valve 72 has a valve member 112slidably mounted therein. The valve proper L13 is adapted to be impelledto a seat 114 whenever the pressure on the face of the piston at the endof the cylinder is suicient -for that purpose. The end of the portion103 of the housing, in which the valve 113 is seated, has pipeline 44which extends from the special valve hereinbefore described, connectedthereto.

.The valve member 112 is provided, midway its extremities, with ashoulder. portion 115, which is adapted to abut against the bushing 104to limitthe movement of the valve member 112. The abutment shoulder 115is channelled lengthwise to permit the air to pass therethrough wheneverthe valve 113 is moved from its seat, by air under pressure comingthrough` pipe line 44, and the housing part 102 is provided with asidewise extending nipple 101 which is connected by pipe line 94, in

whichi the pressure control Valve 95 is interposed, and

which is connected to pipe line 93.

lThe valve member 112 is. also provided, where it passes through thecenter of the bushing 104, with guide lugs l116, for the purpose ofinsuring the proper alinement and seating of the valve 113. The end ofthe valve member 112 is. adapted to be engaged by the piston 107 whenthe piston is actuated by air under pressure from pipe line 73.

The tension of the coil spring 111 is so related to the tension of thecoil spring 57 of special valve 30 as to cause -the specialcontrol valve7-21to Vstop the ow of the air to the brakes from the -pip'e line 44wheneverthe air inthe Areservoir tank has beentraised to a 'safe/work'-ing pressure, whereby the brakes may beroperated `inthe usual manner bythe valves 15 and 16 without lwaiting for the air inthe reservoir `tanksto be raised to the nor mal and higher degree.

'In the pipeline 94 .there is-interposed a pressure control valve which:is ofthernature of` a choke valve, the purpose of thel same being toprevent the sudden application of air to'thebrakes whenever the samehows through the pipe line 494 at-.a relatively high pressure, as willbe hereinafter more V'fully set forth. Valves of this type are availableYand no: special form is necessary.

The pipeline 44, which 'extends froml the nipple 43 of the special valve30, .is also connected by means of a pipe line 96 to a doubleactingvcheck valve 97, which is connected by pipe line 98 to the line 80which' extends to the reservoir tank 12. A pipe line 99 extends from thedouble acting. check valve 97 to the trailer coupling 100, which in turnis connected by pipe line 24 to the trailer relay valve 20.

Inter-posed in the pipe line 23, which extends from the trailer relayvalve 20 to the trailer reservoir tank 17 is a pressure regulating checkvalve 120, of special construction, which is shown more particularly indetail in Fig. 4 of the drawings.

The special valve 120, used in connection withthe trailer reservoir tank17, comprises a housing having a tubular portion 121 in alinement withthe pipe connections, and in this portion 121 there is slidably mounteda valve member 122 having` a stem portion 123 which is uted, and whichis impelled to its seatr 124 by a relatively light spring 125. Thisportion of the valve. opere ates somewhat in the nature of a checkvalve,` stopping the :dow of air into the trailer reservoir tank17,1but`under certain conditions, permitting the outward. ilow of theair to actuate the brakes of the trailer when the pressure is built upin the tank 17 sutciently for its intended purpose in the operation ofthe system. i

The special valve 120 is provided, however, with a sidewise extendingportion 126 provided with transversely extending ports 127 and 128, anda port 129 which provides a communication between the ports 127 and. 128under certain conditions as hereinafter set forth. The port 129 isnormally closed by means of a valve member 130 carried by a flexiblediaphragm 131 which .is se` cured in place by means of a bonnet 132. Thebonnet 132 forms an auxiliary housing for a relatively heavy spring 133,one end of which is seated againstthe dia-z phragm 131 and the other endof which is seated on al be permitted to ow through the ports 127, 129,and 128 into the trailer reservoir tank 17 for subsequent use in theregular manner.

The operation or the apparatus as hereinbefore-described should now bereadily understood.

Under normal running conditions the air in the' tanks 11 and 12 will bemaintained in the proper operating pressure, and also in the line 37,which` extends tosaid tanks from the special valve '30, the air will beat" sub-V stantially the same pressure as that in the tanks 11q and- 12.This will cause the valve member 45 of special valveA 30 to be actuated,through the pressure on the piston 49,

and the end 47 of the valve member 45 which 'would otherwise be seatedon the bushing 39 as shown in Figz' from its-seat against" 2 of thedrawings, will be moved the tension of coil spring 57.

l VWhen the valvel member Y`45 is thus actuated, the air coming fromfthecompressor 10 will ypassthroughithe Yvoir tank 17 Yto'maintairltheproper pressure therein. i

At this time,'the valve member 122 of vspecial valve 120 will .beseated, but .the air under the operating pressure, acting. on thediaphragm 131 against the 4tension of the spring 133, will cause thevalve member 13010 be moved from its seat to permit theV air to passthrough ports `127, 129 and 128, into the .trailer reservoir Vtank 17from which it may subsequently ilow whenever required, for applicationtothe trailer brakes, by moving the valve.122 Vfrom its seat 124 againstthe tension of the spring 125. The spring 125 being relatively light,willA not appreciably interfere Vwith the flow of the air from the tank17 whenever'the same is required.

Also, when the system is working underr normal run. ning conditions,whenever the operator desires to apply the brakes, this is done by theoperation of the foot actuated valvevlS, the air under pressure thenowing from tanks 11 and 12 through pipe line 80 to the foot operatedbrake thence by pipe line 81 to the double actting check valve 82,thence by pipe line 83 to the tractor brakes 13 and 14. A

At the same time, that is, when the foot actuated valve 15 is operated,the air under pressure'willflow through pipe 88 to doubleacting checkvalve 87, thence by pipe line 89 to double acting check valve 90, thence.by pipe line 91y to the trailer coupling 92, thence by pipe line 2S tothe trailer relay valve 20, which, being actuated by the air underpressure coming through pipe line 28, will cause the yair under pressurein the trailer reservoir tank 17 .to flow. through pipes 21 and 22 tothe trailer brakes 18 and 19 respectively.V

.When the system is operating normally, the pressure in Y the trailerreservoir tank 17 will be maintained by the air under pressure owingfrom the main reservoir tanks 11 and 12 topipe 80, to pipe 98; throughdouble acting check valve 97, pipe 99, trailer coupling 100,A and pipeline 24 to the trailer relay valve 20, and thence through pipe 23, inwhich special valve 120 is located, t0V

line 85, handrvalve 16, pipe line 86, double acting checkl valve.87,pipe line 39 to the double acting c heck valve 90, and thence throughpipe line 91, etc., to the trailer relay valve for the operation of thetrailer brakes as aforesaid, but independently of the tractor brakes.

The novel parts of the present invention are providedV for the purpose,of preventing the operation of the vehicle, whenever the pressure ofthe air in the reservoir tanks 11 and 12 falls below a predeterminedsafe limit,

#by the automatic application of the brakes, and the holding of the samein applied condition under such conditions.

, It Awill be noted-thatwhenever the pressureof the air in the reservoirtanks 11 and 12 falls below a predeter-I mined safe limit, therelatively heavy spring 57 of special valver30, bearing against the heador guide member 58, will impel the valve member 45 to the position shownin Fig. 2 of the drawings, whereupon ,the air coming through pipe 34from the compressor 10, will pass. through ports 64, .65 and 66, to. theotherend of the. housing 31 vof special valve 30, passing through thebushing 41, through Ithe ports 60 in the head .or guide member 58, andoutwardly through the bonnet 42` and nipple 43. to pipeline 44, whichextends .,to one end of the special control valve72. 1

The pressure of the air coming'through pipe line 44 from the compressor,will cause the valvemember 113'to be moved from its seat 114,Vpermitting the air to pass to the interior of thehousing part 103 ofspecial control valve 72thence passing throughthe uted stop member-115through the bushing 104 tothe interior of the 'portion 102 of thehousing of the special valve 72. The air thus coming from the compressor10 will pass, through nipple 110 to pipe line 94 Ywhich extends to thecrossconnection line 93 extending between the double acting check valves82 and 90 so that, in thspmanner, whent ever the pressure yin thereservoir tanks 11 and 12 falls` below the predeterminedrsafe amount,and the compressor continues to operate, the air coming from thecompressor 10 will pass through the control valve 72 and thence throughpipe line 93 to double` acting check valves 82 and 90.` The air passingrthrough double acting checkV valve 82 will then pass through pipe line83 to tractor ybrakes13 and 14, and cause the same to be applied.

the trailer brakes Y18 and 19 to cause the sameto be" applied. Y

The brakes will thus be applied Aand remain` appliedv until after'thecompressor has continued to operate for a sucient length of time tobuild up and restor'etheV pressure in tanks 11 and 12, and tank 17 toa'safe minimum limit; and after this has occurred, the operator mayrelease the brakes by a single actuation of the foot operated valvee15,and thus restore the system to condition for normal operation bythe'airv coming from the' tanks 11, 12 and 17. f Y

It should, of course, be understood that when the system` is functioningnormally,'the pressure in the pipe line 80 being transmitted through thepipe line 73 to the end of the special control valve 72 in which thepiston 107'ismounted toY overcome the pressure yof the spring 111 andwill engage the valve member 112 and cause the valve portion "113thereof to be impelled to its seat 114, and' thus prevent ilow frompipeline 44 under normal operat-j ing conditions.

` Thefspring 111 of the special control valve 72 is of such tension asto cause the valve member 113 thereof' to be seated'so thatthe brakesmay be used in the normal'v manner as soon as a safe working pressurehasbeen ob" tained in the reservoir tanks 11 and 12,4 and tank 17,V

without Waiting-for the pressure in said tanks to be' raised' to thehigher degree maintained' inV said reservoir tanks in the normaloperation of the system. Y

It should also be-understood that whenever the pressure.- in thereservoir tanks falls below the safe minimumV limit and the specialvalve 30 is actuated to causc"the air comingrfromV the reservoir ow intopipe line l44, at, the same time a portion ofthe air will ow'throughpipe line 96, thence through double acting check valve 97,V

pipe line 99, coupling and pipe line 24 tothe trailer relay valve 20 forutilization in restoring the'pressure in operating ae'aayrse d extendingfrom said compressor tosaid tank; ,airfoperated brakes, piping extendingfromsaid tank to 'said brakes, and manually operable v means forcontrolling the ow of air through' the piping from said tank to saidbrakes for the ordinary operation thereof, the combination therewithofmeans for automatically causing the airto pass directly from thecompressor to the brakes thereby to apply said brakes, and to maintainsaid brakes applied, when the pressure in the reservoir tank falls belowa predetermined normal operating,amount,.said means comprising anVautomatic contro1`valve connected tothe piping which extends fromthe-compressor tothe tank, which valve normally has its Vvalve memberheld in position by the tank pressureto permit the air to `iiow from thecompressor tothe-tank, aspring tending to shift said valve member tostop -the flow of the air to the tank, a pipe line extendinglfrom'saidcontrol valve sor is diverted directly to the brakes when the valvemember is shifted by lthe aforesaid spring, meansin said control valvefor causing the `air yfrom thercompressor to pass to the reservoir tankafter apredeterm'ined pressure hasbeen reached in said pipe line, andasecondautomatic control valve in said pipe line, said second automaticcontrol valve being actuated by the tank pressure to prevent deliverythrough saidpipe line to the brakes when lthe tank pressure reaches avalue less` than the normal operating amount.

2. Inan air brake system for automotive vehicles'of the` tractor trailertype, including an airicompressor, an air reservoir tank for thetractor, .pipingextending from said compressor tofsaid tractorftank, airoperated brakes onthe tractor, an airA reservoir tank Ifor the trailer,air operated brakes on the trailer, pipingextending from said tractortank to said tractor brakes and said'trailer brakes,.a relay valve onthe trailer, and manually operable valve means for controlling the flowof airthrough the piping from said tanks to said'` brakes for theordinary operation thereof, the combination therewith. of means forautomatically causing the'air to pass directly from the compressor t-othe brakes thereby to apply said brakes, and'to maintain said brakesapplied, when the pressure-inthe tractor tank falls below apredetermined normaloperating amount, said means comprising a firstautomatic controlvalve connected to the piping which extends from thecompressor to the tractor tank, which valve normally has its valvemember held in position by thetractor tank pressure to permit the zurto-ow fromfthe--compressor to the tractor tank, Va spring tending toshift said valve member 'to lstop'the ow of the air to the tractor tank,a pipeline extending from said first automatic control valve to thetractor brakes through which the air from the compressor is diverteddirectly to the tractor brakes when the valve member -is shifted by theaforesaid spring, means in said rst control valve for causing the airfrom the compressor to pass to the tractor tank after a predeterminedpressure Ihas been reached in said pipe line, a second automatic controlvalve in said pipe line, said piping from said tractor tank to saidbrakes having a pipe line extending therefrom to said second automaticcontrol valve for applying the tank pressure at said second controlvalve to prevent air delivery through said first pipe line to the brakeswhen the tank pressure reaches a value less than normal operating value.

3. In an air `brake system for automotive vehicles of the tractortrailer type, including an air compressor, an air reservoir tank for thetractor, piping extending from said compressor to said tractor tank, airoperated brakes on the tractor, an air reservoir tank for the trailer,air operated brakes on the trailer, piping from said tractor tank tosaid tractor brakes and said trailer brakes, a relay valve on thetrailer, and manually operable valve means for controlling the flow ofair through the piping from'. said tanks to 'sidvbrakes'forrthe"ordinaryone@ vtion'thercof,"'the 'combination therewith of meansI forautomatically. causing :the air. to 'pass' directly' from: thecompressor to the brakesA thereby 'to applysaid brakes, and to maintainsaid brakes applied, when the pressure in the tractor reservoir tank-fallsbelowV apre'determined normal operating. amount, said means.comprising a rst automatic control`valve interposed iin the'piping`which extendsifrom the compressor. to thetank, which valve normally hasits lvalvenlemberheld in position by 'the tractor tankpressuretorpermtthe'air to ow from the compressor. to thetractor tank, a spngftendingtoshift said yvalve`-member Yto stop theflow 'ofthe air to the tractortank, apipe line extending'from' said rst'control valve tothe Itractorbrakesthrough which the airfr'om .the compressor is'xiiverted directlytothe tractor brakes when. the valve-member: is shifted-by the aforesaidspring, -means in said .'iirst control valve member for causing the'y'from'th'e compressor to pass to the tra'ctorreservoirtankafter a`predetermined pressure has been reached inrsaidcpip'e linel thereby'to.restore the air ;insaid tra'ctor tank` to normal operating pressure,-andfasecond automatic control valve in said pipe-.line said4pipingffromith'e .tractor .tank 'to said' brakes includingapipe-lineeextending therefrom to said second automatic controlvalvefor.applying at said second automatic contro1-valve thenormalxoperating'tractor tank pressure to vclose saidvalvev and preventdelivery through said first Vpipe line to said brakes upon attainmentofta predetermined pressure in said tank, said piping from Vsaid tractortankfto said brakes. including a fluid connection tothe'trailerirbrakes, thereby to cause the trailer brakes to be appliedsimultaneously with the tractor brakes Whenlthev pressure'in thetractorand' trailer rese ervoir tanks'. falls below the. predetermined normaloperating amount. v c

4. Inv an airxbrake system .forautomotiveveh'icles of the-tractortrailertype, .includingian air compressor, 'an air reservoir tank Iforthe. tractor, piping extending. 'from said compressor to said" tractortank, air operated brakes on the tractor, an air. reservoir tank for thetrailer, air operated brakes'on the trailer, piping extending. from saidtractor tank tol'said tractor brakes and. to 'said trailerbrakes, -arelay valve: on the trailer, .andimanually operable valve means forvcontrollingthe'flowl of air through thepiping from said vtankstorsaidbrakesffor the ordinary operation thereof, the combinatontlerewith of means for automatically 'causing theia'ir toipass directly fromthe compressor to the brakes `thereby to apply Asaid brakes, and tomaintainesaid brakesa'pplied,

When1the pressure'in the ltractor `reservoir tank falls-be# low a.predetermined normalv operating amount, said means comprising a rstautomatic control valve-con-Y nectedto the piping which extendsfrom thecompressor to the tractor tank, which valve normally has its valvemember held in position by the tractor tank pressure to permit the .airto Viiowl from theY compressor to. the tractor tank, a spring tending toshift said va-lve member to stop the ow of the air to the Vtractor tank,a pipe line extending from said first .control Valve tothe tractorbrakes throughV which theair from the compressor is diverted directly tothe tractor brakes when the valve member is shifted by the aforesaidspring, means in said rst control valve for causing the air from thecompressor to pass to the tractor reservoir tank after a predeterminedpressure has been reached in said first pipe line, a second automaticcontrol valve in said pipe line, said piping from said tractor tank tosaid brakes having a pipe line extending therefrom to said secondautomatic control valve for applying the tank pressure at said secondautomatic control valve to close said valve and prevent air deliverytherefrom to the brakes, said piping from the tractor tank to the brakesincluding fluid connections to the trailer relay valve and 1 1 to thetrailer reservoir tank thereby to cause the trailer brakes to be appliedsimultaneously with the tractor brakes When the pressure in the tractorandtrailer reservoir tank'sfalls below thepredetermined normal operat-Ytrailer brakes, a relay valve onlthetrailer, and manually operablevalve'means -for controlling the ow of air through the piping from said`tanks to said brakes Vfor theA ordinary operation thereof, thecombination there- Ywith of means for automatically causing the air topass directly from the compressorgto the brakes therebyrto apply saidbrakes, and toY maintain said brakes applied, when the pressurein thetractor reservoir'tank falls below a predetermined normal operatingamount, said means comprisingA a rst automatic control valve. connectedto the piping'which extends from the compressor to the brakes, whichvalve normally has its'valve member held in position by the tractor tankpressure to permit the air to flow from the compressor Vtothe tractortank,ia. spring tending: to shift said valve Vvmember to stop the llowof the air to the tractor tank, a pipe line extendingfrom said rstcontrol valve to the tractor brakes through'which theair`fron1 thevcompressor is diverted directly to the tractor brakes when the valvemember is shifted by the aforesaid spring, means in said rst'controlvalve for causing Ythe air from the compressor-to pass to the tractorreservoir tanktafter a predetermined pressure has been reached in saidpipe line thereby to restore the air'in said tractor tank to normaloperating pressure, a second automatic control valve in said pipe line,said piping from said tractorttank to'said brakes 'having apipe lineextending therefrom to jsaid second automaticcontrol valve `for applyingthe tractor tank pressure at saidV second automatic control valve toclose said valve and preventing air delivery therethrough to the brakes,said piping from' said tractor tank to said brakes includingfluidrconnectionsV from said first pipe line to the trailer relay valveand tothe tractor reservoirrtankV and a iluid connection from thevtrailer relay valve to the trailer reservoir tank, thereby to` causethe t trailer brakes to be applied simultaneously with 'the tractor.brakes when t-he pressure in the tractor and trailer reservoir tanksfalls l below 'the predetermined 'normal operating amount, and 'saidpiping from said tractor tank to said brakes also having ya branchpipeline extend# ing from said iirst'pipe line to the uidconnection'which extends from the tractor reservoir tank to'thejtrailerre`- layvalve. y 'i' 6. tIn'an air brake system for automotive vehiclesof the tractor trailer type, including an air compressor, an airreservoir` tank for the tractor, piping extending from said compressorto said tractor tank, air` operated brakes on the tractor, anrairreservoir tank for the trailer, air

Voperated brakes on thetrailer, piping extending 'from said tractortankl to said brakes, a relayr valve on the trailer,land manuallyoperable vvalve means for controlling .the ow of air through Y- thepiping from said tanks to said brakes for the ordinary operationthereof, the combination'therewith of means for automatically causingthe air to pass directly from the lcompressor-to the'brakes thereby to-apply said brakes, and to maintain said brakes applied, when thepressure in the tractor reservoir tank -falls below a predeterminednormal operating amount, said means comprising an automatic controlvalve connected to the piping which extends from the compressor to thetractor tank, which valve -normally has its valve member held inposition by the tractor tank pressure to permit the lair to ilow fromthe compressor to the tractor tank, a spring tending to shift said valvemember to'stop the ow kof the air to the tractor tank, a pipe lineextending from said irstl controlr valve to the tractor brakes' throughwhich the air from?.

the compressor is `diverted directly to the tractor brakes, when thevalve member is shifted -by the aforesaid spring, means Yincluding saidrst control valve for causing the air from the compressor to kpass tothe tractor reservoir tank after'a predetermined pressure has beenreached in said pipe line thereby to restore the air in said tractortank to normal operating pressure, a lsecond automatic vcontrol valve insaid pipe line extending Vfrom the rst automatic control valve to thetractor brakes, s aid piping from said tractor to said brakes includinga pipe line extending therefrom to saidsecond-automatic control valvefor applying the tractor tank pressure at said second automatic control'valve to close said valve and preventV air delivery therethrough tothe'brakes, said piping from said tractor tank to said brakes alsohaving a :branchvpipe line extending to the trailer relay valve `from4said first pipe line tothe tractor brakes, a pipe line extending fromthe tractor reservoir tank tothe trailer relay valve, anda pipe lineconnecting the trailer relay valve to the trailer reservoirtankthereby'to cause the trailer brakes to be appliedsimult-aneous'lywiththe Y tractor brakes when the pressure in the tractor and trailerRefereneesCited in the tile of this patent STATES PATENTS v 1,797,431-Mathieson Marll 24, 1931 2,402,115 Levy a Q Iunell, 1946 2,578,388Ambler f -n Dec.-11, 1951 V2,680,500 Jenkins i June 8, 1954 2,792,916Williams May 2l, 1957 2,834,638

George May13v,v195s g

